house a/c generator

Discussion in 'General Electronics Chat' started by samjesse, Oct 17, 2009.

  1. samjesse

    Thread Starter Active Member

    Sep 14, 2008

    How much horse power an electrical generator needs to run? I mean for an average house electrical needs.

    are we talking about more than 5 to 10 or 10 to 50... horse power.

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Grab some figure for the electrical load, say 100 amps (most modern houses have 200 amp service). 100 amps X 120 volts = 12,000 watts. One HP is 748 watts, so 12,000/748 = 16.04 HP.

    Nothing is 100% efficient, so figure more like 30 HP to run the alternator. One man in the 1920's rigged a Model T Ford engine to supply his electricity and hot water needs.

    If you buy a generator set, the manufacturer will have a properly sized engine included.
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    In my house, just the bare necessities to get by include a refrigerator, a freezer, a few lights, and the gas furnace blower for a total of 5kW. Starting the induction motor in the furnace is the most problematic. The ratio of starting current to running current in a fractional horsepower induction motor (like in the furnace, fridge, and freezer) is about 15:1, so it takes large generator to provide the motor inrush current.